The Office of School Design and Charter Partnerships (OSDCP) at the New York City Department of Education (DOE) developed and executed a plan for district-charter collaboration, which they called the District-Charter Partnerships (DCP) initiative. This document describes the results of a mixed-method study of DCP conducted during the 2016-17 school year, which was the first full year of DCP implementation. Drawing on surveys, interviews, and program observations, it highlights promising practices for structuring and fostering deep and meaningful cross-sector collaboration, as well as the challenges and early outcomes of these efforts. It concludes by highlighting structures developed to achieve sustainability of DCP, so that both sectors continue to work in partnership to ensure that there is equity and excellence for all New York City students.